Saudi Arabia's King Abdullah arrives in a wheelchair at JFK airport.REUTERS

RIYADH, Saudi Arabia — Saudi King Abdullah arrived Tuesday in New York for medical treatment, the country’s official news agency reported, after he temporarily handed control of the world’s top oil producer and key American ally to his half brother and heir to the throne the day before.

The 86-year-old monarch was greeted by Saudi Foreign Minister Saud al-Faisal and a number of top Saudi officials after landing at New York’s John F. Kennedy airport, Saudi Press Agency said. It published photographs showing Abdullah in a wheelchair at JFK, shaking hands with al-Faisal.

It was not immediately known where Abdullah would be receiving treatment in the United States. A statement from the palace said only that he would be undergoing “medical tests.”

In Washington, the State Department said Monday that it helped facilitate clearances for the king to come to the U.S. for treatment.

“The king is a valued partner,” department spokesman P.J. Crowley said. “We wish him a speedy recovery. I don’t know that we have any particular concerns about his health. We want to see him up and about as quickly as possible.”

Before he left, Abdullah issued a royal decree mandating Crown Prince Sultan, his half brother and heir to the throne, to “administer the nation’s affairs” in his absence.

Abdullah has temporarily handed over authorities in the past when he has traveled abroad for conferences or personal trips, though this was the first time for health reasons.

Monday’s smooth transfer of power from one brother to another served as a reminder of the advancing age of the generation of the royal Al Saud family that has ruled the kingdom for the past 60 years. It also revived a long-standing question that may be taking on greater urgency: Can the rulers maintain stability when it comes time to pass the throne to a new generation.

The 85-year-old Sultan — also the defense and aviation minister — has his own health issues: He underwent surgery in New York in February 2009 for an undisclosed illness and spent nearly a year abroad recuperating in the United States and at a palace in Agadir, Morocco.

Before the king headed for New York, Saudi officials had been making a strong push to reassure the public and international allies there is nothing to worry about.

Health Minister Abdullah al-Rabeeah said Monday the king suffered a slipped disc and that a blood clot was pressing on nerves in his back, causing him pain and so he was heading abroad for treatment.

“But I assure everyone that the king is in stable condition and enjoys good health and God willing will return in good health to lead this great nation,” al-Rabeeah said.

Abdullah rose to the throne in 2005 after the death of King Fahd, though he had already been a de-facto ruler for half a decade.